They can be converted but it still doesn't solve the basic flaw in the design. Both jets share a common passage with the APT system. Without completely blocking off the passages between them they never work as well as the later design. I avoid those carb here, at least they are my LAST choice for building a custom high performance unit. I've ran into enough of them over the years that didn't work well no matter what I did to they to learn to stay clear of them altogether.
The factory must have known about the issues and why they only saw a brief run back in 1975 and early 1976......IMHO.....
